评价指标

I

II

III

IV

V

氨氮( $N{H}_4^{+}\text{-}N$ )

≤0.02

≤0.02

≤0.2

≤0.5

>0.5

硝酸盐( $N{O}_3^{-}\text{-}N$ )

≤2

≤5

≤20

≤30

>30

亚硝酸盐( $N{O}_2^{-}\text{-}N$ )

≤0.001

≤0.01

≤0.02

≤0.1

>0.1

总磷(TP)≤

≤0.02

≤0.1

≤0.2

≤0.3

>0.4

总氮(TN)≤

≤0.2

≤0.5

≤1

≤1.5

>2